Arthroscopic Microdrilling for Full-Thickness Trochlear Cartilage Defects in Patients Undergoing High Tibial Osteotomy Confers Improved Cartilage Status at 1 Year and Rate of Minimal Clinically Important Difference at Short-Term Follow-Up

Abstract

Purpose: To compare the patient-reported outcome (PRO) improvements and cartilage status of trochlear cartilage defects (TCDs) after additional arthroscopic microdrilling versus no treatment for TCDs during medial open-wedge high tibial osteotomy (MOWHTO).

Methods: Patients who underwent MOWHTO with either microdrilling (group M) or no treatment (group N) for near full-thickness TCDs (International Cartilage Repair Society grade IIIB or greater) from March 2010 to September 2022 were retrospectively reviewed, with a minimum 2-year follow-up. 1:1 Propensity score-matched group N was created. Comparative analyses were conducted using PROs and minimal clinically important difference (MCID). Trochlear cartilage status was assessed visually via second-look arthroscopy 1 year postoperatively and categorized as deteriorated, maintained, or improved.

Results: Overall, 30 patients for group M and 84 patients for group N were included. The mean follow-up periods of the matched groups were 32.8 and 32.0 months for groups M and N, respectively. The preoperative and postoperative radiographic parameters did not differ between the groups (Kellgren-Lawrence grade, pre- and postoperative alignment, medial proximal tibia angle). Both groups achieved significant clinical improvement in patients with medial compartment osteoarthritis and combined full-thickness TCD (P < .001). PROs and improved PROs at final follow-up were not significantly different between groups, except for the Final Kujala anterior knee pain scale (70.4; 95% confidence interval 66.0-74.8 vs 59.8; 95% confidence interval 53.0-67.6, P = .018). MCID achievement rates in pain visual analog scale (VAS), Knee injury and Osteoarthritis Outcome Scores (KOOS)-pain, and KOOS-activity of daily living (ADL) were significantly greater in group M compared with group N (VAS, 93.3% vs 63.3%, P = .005; KOOS-pain, 96.7% vs 80.0%, P = .044; KOOS-ADL, 86.7% vs 63.3%, P = .037). A significantly larger proportion of patients in group M showed improvement in their TCD status compared with those in group N (93.1% vs 44.8%, P < .001).

Conclusions: Arthroscopic microdrilling for near full-thickness TCD during MOWHTO improved trochlear cartilage status at 1 year but did not enhance final PROs at short-term follow-up, although it increased MCID achievement rates in some PROs (VAS, KOOS pain, KOOS ADL) compared with untreated patients.